Male underpants are frequently manufactured to incorporate a fly through which the penis can be withdrawn in order to allow urination without lowering of the underpants. Very frequently, the outer garments, such as shorts or pants, also have a fly which is generally aligned with that of the underpants and must be opened first to allow access. While the use of the fly (or files) is generally considered more convenient (and socially acceptable) for urination than simply dropping one's trousers and underpants, difficulties still exist.
For instance, body movement will often cause the underpants to twist or otherwise move relative to the outer garments such that their respective flies are no longer aligned and/or that the fly of the underpants is generally not where one would expect to find it. An undesirable delay can be incurred as a result of the need to locate the opening flap of the underpants fly in order to gain the necessary access. This delay is particularly problematic in the case of persons with arthritis, hand or wrist injuries, or other conditions affecting manual dexterity, as well in the case of individuals with bladder control problems.